Blitter based full screen parallax (64 colour minimum on AGA)

[ImmortalA1000]

I was wondering if anybody knows of a game or demo that replicates arcade quality parallax that uses the hardware in the most advanced way (not 15 colour anaemic OCS/ECS dual playfield zzzzzzzzz)

Specifically I am wondering if anybody ever wrote a routine that blits everything (so no background to be saved and speeding up blits) every frame and hence builds up a software parallax via the hardware.

Would help if I knew what the maximum number of blitter max megabytes per second or per "frame" (1/25th or 1/30th of a second) or "field" (1/50th or 1/60th of a second)

Must be full screen fully overlaid parallax layers, not raster/copper based horizontal business that doesn't overlap.

Not sure how much faster blind blits are compared to ones that do save/restore background being blitted over.

double buffered only I guess

("frame" in CRT engineer terms = two fields of half PAL/NTSC vertical broadcast resolution displayed in sequence via the cathode ray beam NOT millennial term of FPS lol)

[Codetapper]

I'm pretty sure both Flimbo's Quest and Toki (a small part of level 1) do parallax "properly" but neither are anywhere near full screen. Most others use some kind of tricks to avoid having to boot as much as it works appear to need.

[Jobbo]

This is what Xenon2 does and it’s only 16 colors. So expect results similar that!

[Jobbo]

There seems to be an awful lot of threads started that speculate about what could be done on the Amiga. But not a lot of concrete number crunching to ground those discussions in reality.

So, here are some basics about blitter performance:

- Max performance for a block copy is only 4meg per second!
- At 50hz that amounts to 80k per frame.
- One 320x256 16 color screen is already 40k.
- Performance for cookie-cutter bobs is half of that!

So, best case you have enough blitter bandwidth to copy one 16 color screen worth of background and then cover half of that with 16 color bobs.

If you actually want the screen mode to display more than 16 colors then the bitplane DMA blocks the blitter some of the time. You effectively get less blitter bandwidth while needing to do more work for those extra colors.

In short, it is really quite slow!

[dlfrsilver]

Originally Posted by Codetapper

I'm pretty sure both Flimbo's Quest and Toki (a small part of level 1) do parallax "properly" but neither are anywhere near full screen. Most others use some kind of tricks to avoid having to boot as much as it works appear to need.

For Toki this is because they used only 512kb of ram. With 1 or 2mb of chip, Toki could had a bigger screen.